Conventionally, an operator's cab having a device fastening the ajar door is constructed as in a perspective view shown in FIG. 6, and details of the device, indicated and are shown in the perspective view in FIG. 7, an elevational view in FIG. 8 and a top plan view in FIG. 9.
More specifically, a door 2 is swingably fixed to a side 3 of an operator's cab I by means of a hinge 4. A lock member 40 having a lock element 41 is fastened near the hinge 4 above the door 2 by means of a bolt 42. A bracket is attached to a position corresponding to the lock member 40 above the side 3, and a lock 50 is fastened by a bolt 55. The lock 50 includes a hook 51, a bracket 52, a pin 53 and a torsional spring 54 wherein the hook 51 is secured pivotally to the bracket 52 by means of the pin 53 and is urged in the direction of the arrow P (FIG. 8) by means of the torsional spring 54. The door is ajar and fastened by swinging the door 2 on the hinge 4 so as to allow the lock element 41 to push up the hook 51 against the urging force of the torsional spring 54 and to engage the hook 51 at the position indicated by chain double-dashed lines in FIGS. 8 and 9. The lock is unfastened by pushing up the hook 51 manually, thereby allowing the door 2 to close.
However, the foregoing construction has the following problems:
(1) Since the fastening device is fixed adjacent to the hinge of the door, the distance L.sub.2 (FIG. 9) between the center of the hinge and the center of the lock is small, and the lock is heavily burdened. Consequently, the fastening device has to be large and costly. PA0 (2) Since the fastening device greatly protrudes at the top of the operator's cab, it might be damaged by obstacles and does not present a good appearance. PA0 (3) Someone has to take the trouble to go out of the cab and release the lock manually to unfasten the ajar door, and this is operationally inconvenient. PA0 (1) The distance L.sub.1 (FIG. 4) between the center of the hinge and the center of the fastening device is greater, and thus the device is not so heavily burdened and accordingly the fastening device can be small. PA0 (2) Since the fastening device does not protrude from the top of the operator's cab, it will not be damaged by obstacles. The tubular support element also functions as a handle outside of the operator's cab, and presents a good appearance. PA0 (3) It is operationally convenient to unfasten the ajar door from inside the operator's cab.
In view of the foregoing problems, an object of the present invention is to provide a device for fastening the ajar door which device is small in size, presents a good appearance, and is easy to unfasten.